Taaltreffers (“Word Score”) is an online serious game intended to increase the vocabulary of pupils in primary schools in the 10-12 age range. The game and the additional materials are designed with the model of Verhallen and Verhallen, in which words are presented in four stages: activating previous knowledge, explaining new words, consolidating new words and testing if the words are part of the daily vocabulary. The game has been piloted at ten schools and the evaluation shows that the vocabulary of the students has increased significantly after playing the game.